Power-driven tool for dressing commutators.



R. S. FREEMAN.

POWER DRIVEN TOOL ma DRESSING OOMMUTATORS.

APPLICATION PILID NOV. 21,1910. 990,722. Patented Apr. 25, 1911.

MN N 2:: 1? u 1 W ee in enrich...

ROE S. FREEMAN, 01 ATLANTA, GEORGIA.

lllltlEJ'iET'E.

Specification of Letters Patent.

Patented Apr. 25, tl'tl lti.

' Application filed November 21, 1910. Serial Noflaflfififii.

To all whom, it may concern:

lie it known that l, ltoe S. l nnmii-iu, a citizen of the United States,residing; at Atlanta, in the county of Fulton and State of Georgian haveinvented certain new and use l'ul improvements in Pmverdh'iveu Tools't'or Dressing (knnmut-ators, ot' which the following is aspecification.

My invention relates to power driven hand tools, and more particularlyto a too] ot tlm character especially designed for dressing thecommututors ol' dynamo electric machines.

As is well known, trouble is constantly experienced with commutator-sowing to the tendency of the relatively soft copper bars to wear awayfaster than the mica used as insulation between them. This results inthe formation of ridges on the eonnnutator which has the eti'ect ofproducing disstrolls sparking. .l leretotore in order to dresscommutator-s worn in t'his'n'ianner, it has been necessary to remov vthe armature from the in: chine in order that" the commutator may hebrotw l'it in position to be operated upon by a milling mach ne orcutter of any well known type.

The primary object of the present invention is to obviate the necessityfor removingthe armature from its hearings and to this end. theinvention seeks to provide a hand tool driven by means of a flexible slaft, and so designed that it; may be used to cut the mica from betweenthe commutator bars without: removing the armature from the machine.

A further object; is to provide a strong.

compact and practical power driven. hand tool of this character whichwill ellectirely perform the work which it is designed to ac- COHIPllSl)and \Vllltll, at the same tune, \\'lll he cxtren'iely cheap and simplein construe non.

With the above objects in view, the'invention consists in theconstruction and an rangementof parts hereinafter described and claimed,and illustrated in the accompanying drawing, in which,

Figure 1 is a plan view otmy com plete device showing the same inposition on a commutator; Fig. 2. is a side elevation of the same; Fig.3 is a central horizontal section. parts being in elevation; and, Figs.4 and 5 are a detail elevation and section respectiveiy, showing themethod of mounting the supporting arms hereinafter described.

Referring to the drawings in detail, my improved tool comprises a handlel which may he formed of wood or othersuitiiible material. To thishandle secured, as by means of a screw shank J, a forked yoke 3. Securedin openings in this yoke are a pair of alined hearings l, 5, held inposition in the yoke by means of set screw t3. Journaled in thesehearings is a shaft 7 over the end of which is adapted to lit a socket 8attached to a flexible shaft 9.

Mounted on the shaft 7 between the forks of the yoke a. milling cutter10 in the na ture of a circular saw and this cutter is held in place onthe shaft by means of (-ilan'iping nuts 11. 12 screw threaded on theshaft. in this connection, it will be observed that the diameter ofthese nuts is less than that of the hearings 4-, 5, whereby. when one ofsaid hearings is removed from its fork, the shatt'. together with theclamping nut on that side, may he shifted laterallv through the openingin the fork left. by the hearing" so that the nut on the other side maybe unscrewed and thus the shaft and first mentioned nut may be withdrawnentirely from the forks thus permittiugthe cutter to be removed.

Referring partieul rly to Fig. 2, it will he observed that the depth orwidth of the yoke l is almost equal to the diameter of the cut ter. It.will also he observed that the ends of the forks, are substantiallysemicircular in shape as indicated at 3. it will tltere- 'tore heobserved that owing to this shape and proportion of the parts the teethof the.

cutter project slightly beyond the edge of the forks and thus when thetool is applied to a commutator such as t3, the bottom ed a e of theforks rest upon su h commutator and serve a support to guide the cutteralong: the work. in order however to even more etl'ectively steady thecut ter and to support it when operatingat the end of the commutator, asshown in the drawings. i provide supporting arms 15, one of which issecured to the outside of each fork. Such arms are preferably slidahlymounted upon the yoke as by means of a barrel or casing 16 tl'irdugghwhich the arm is adapted to slide and in which is disposed a coil springl7 surrounding the arm. A pin '18 passing through they arm engages suchspring and also projects through a slot. it) formed in the barrel. Thisconstruction. it will be seen, permits the arms to yield when they arebrought in con tact with the end wall 14 of the commutator so as toallow. the cutter to travel as far as the end of the yoke will permit.

d it. Wnl thus be seen that I have provided a small, compact and at thesame time substantial power drivem hand tool which can bereadiiy'upplied to any commutator without remov'ingit from its normalposition and it is thought that the manyadvanteges of my Y inventionwill be readily appreciated by those familiar with such matters.

What I claim is: l. A tool for dresslng oommutators com- I prising ehandle, a forked yoke carried thereby, a shaft extending throu h and journeled in both forks of said yo'e, a cutter mounted on said shaftbetween the forks of the yoke, and a supportin arm secured to eaeh sideof saidyoke parallel therewith and projeotinghe end the end'thereof.

2. A tool or dressing commutators comprising a handle, a forked yokecarried thereby, ashaft journaled in said yoke, a cutter mounted on saidshaftbetween the forks of the yoke, a supporting a'rm slidably.

mounted on each side of said yoke, and re silient means for normallymaintaining said arm projected beyond the end of said yoke.

3. A tool of the class described, comprising. a forked yoke, 21 pair ofalined bearings carried by the forks of said yoke, a shaft journaled insaid bearings, a millin r cutter mounted on said shaft'between the iorksof said yoke, and clamping nuts fitted one-aid shaft and serving to holdsaid cutter in position,one of said bearings being removable, 1

